Ag掺杂对La_(0.67)Sr_(0.33)MnO_3磁性和导电性的影响机制研究
|
摘要
稀土掺杂锰氧化物材料La_(0.67)Sr_(0.33)MnO_3(LSMO)的顺磁-铁磁转变温度(Tc)高于室温,在自旋电子学等领域有广泛的应用前景.近年来的研究表明,Ag掺杂能有效改善LSMO的晶粒尺寸和导电性能.本文中采用溶胶-凝胶法制备了La_(0.67)Sr_(0.33)MnO_3:Agx(x=0,0.5%)多晶粉体.采用X线衍射(XRD)、扫描电子显微镜(SEM)、振动样品磁强计(VSM)和X线光电子能谱(XPS)多种技术,测试了Ag掺杂前后LSMO的微观形貌、晶相结构、电阻率、磁滞回线、Ag和Mn元素价态变化.分析表明:一部分Ag以单质形式存在于LSMO晶粒边界,增强了导电性;另一部分Ag进入晶格,替代了钙钛矿结构ABO3的A位La离子,使LSMO中出现少量La2O3杂相,并使Mn3+/Mn4+比例降低,削弱了双交换作用,因此LSMO的磁性减弱.Ag替代La还使LSMO的少数自旋子带带隙略减小,对提高导电性有次要的负作用.
Rare-earth doped manganese oxide La_(0. 67)Sr_(0. 33)MnO_3(LSMO) has broad application prospects in the field of spin electronics,which has the paramagnetic-ferromagnetic transition temperature( Tc) above room temperature. Recent research shows that Ag-doping has effective improvements of grain size and conductivity of LSMO for improving the colossal magnetoresistance effect( CMR). In this paper,sol-gel method was used to prepare La_(0. 67)Sr_(0. 33)MnO_3:Agx(x = 0,0. 5%) polycrystalline powder. By X-ray diffraction( XRD),scanning electron microscopy( SEM),vibrating sample magnetometer( VSM) and X-ray photoelectron spectroscopy(XPS) technologies,the microstructure,crystalline phase structure,resistivity,magnetic properties,Ag and Mn valence states of LSMO were tested before and after Ag doping,respectively. The analysis shows that some Ag atoms exist at the grain boundary of LSMO in the form of element to enhance the conductivity,and other Ag atoms go into the crystal lattice replacing A site La~(3+) in the perovskite structure ABO3,which obtains a small amount of La_2O_3 hybrid phase in LSMO and decreases the ratio of Mn~(3+)/Mn~(4+). Ag doping weakens the double exchange effect and the magnetic property of LSMO. The substitution of La with Ag also makes minority spinon band of LSMO slightly reduced,which can weakly decrease the conductivity of LSMO.
Rare-earth doped manganese oxide La_(0. 67)Sr_(0. 33)MnO_3(LSMO) has broad application prospects in the field of spin electronics,which has the paramagnetic-ferromagnetic transition temperature( Tc) above room temperature. Recent research shows that Ag-doping has effective improvements of grain size and conductivity of LSMO for improving the colossal magnetoresistance effect( CMR). In this paper,sol-gel method was used to prepare La_(0. 67)Sr_(0. 33)MnO_3:Agx(x = 0,0. 5%) polycrystalline powder. By X-ray diffraction( XRD),scanning electron microscopy( SEM),vibrating sample magnetometer( VSM) and X-ray photoelectron spectroscopy(XPS) technologies,the microstructure,crystalline phase structure,resistivity,magnetic properties,Ag and Mn valence states of LSMO were tested before and after Ag doping,respectively. The analysis shows that some Ag atoms exist at the grain boundary of LSMO in the form of element to enhance the conductivity,and other Ag atoms go into the crystal lattice replacing A site La~(3+) in the perovskite structure ABO3,which obtains a small amount of La_2O_3 hybrid phase in LSMO and decreases the ratio of Mn~(3+)/Mn~(4+). Ag doping weakens the double exchange effect and the magnetic property of LSMO. The substitution of La with Ag also makes minority spinon band of LSMO slightly reduced,which can weakly decrease the conductivity of LSMO.
引文
[1]Zener C.Interaction between the d-Shells in the transition metals(II):ferromagnetic compounds of manganese with perovskite structure[J].Phys Rev,1951,82:403.
[2]Beatriz R M,Irene L,Pilar J C,et al.Independent control of the magnetization in ferromagnetic La2/3Sr1/3Mn O3/Sr Ti O3/La Co O3heterostructures achieved by epitaxial lattice mismatch[J].Nano Letters,2016,16(3):1736.
[3]Barrionuevo D,Zhang L,Ortega N,et al.Enhanced tunneling electroresistance in Pt/PZT/LSMO ferroelectric tunnel junctions in presence of magnetic field[J].Integrated Ferroelectrics,2016,174(1):174.
[4]Huang W,Lin Y,Yin Y,et al.Interfacial ion intermixing effect on four-resistance states in La0.7Sr0.3Mn O3/Ba Ti O3/La0.7Sr0.3Mn O3multiferroic tunnel junctions[J].ACS Appl Mater Interfaces,2016,8(16):10422.
[5]Tan Y,Ju D Y.Electrical properties of Ag-La0.67Sr0.33Mn O3[J].Mater Sci Forum,2011,675/677:1101-1104.
[6]Moshyaga V,Belenchuk A,Huhn S,et al.Intrinsic antiferromagnetic coupling underlies colossal magnetoresistance effect:role of correlated polarons[J].Phys Rev B,2014,89:024420.
[7]凌一峰,刘翔,陈清明,等.固相法制备La2/3Sr1/3Mn O3:Agx多晶材料及其性能研究[J].热加工工艺,2013,42(16):25.
[8]殷学鹏,晏益志,陈清明,等.溶胶-凝胶法制备La0.67Sr0.33Mn O3:Agx多晶材料及其性能[J].热加工工艺,2014,43(20):84.
[9]刘翔,晏益志,陈清明,等.Ag掺杂对La2/3A1/3Mn O3(A=Ca、Sr、Ba)材料电学性能的影响[J].无机材料学报,2013,28(12):1307.
[10]张少春,刘翔,张辉,等.La2/3Ba1/3Mn O3:Agx多晶靶材制备及其性能[J].材料热处理学报,2013,34(6):1.
[11]Li J,Huang Q,Li Z W,et al.Microstructure modification and magnetoresistance enhancement by Ag doping in La2/3Sr1/3-Mn O3thin films prepared by dual-beam pulsed laser ablation[J].J Phys Condens Matter,2001,13:3419-3431.
[12]晏益志.Ag掺杂LSMO材料制备及LIV效应研究[D].昆明:昆明理工大学硕士学位论文,2014.
[13]Snyder G J,Hiskes R,Dicarolis S,et al.Intrinsic electrical transport and magnetic properties of La0.67Ca0.33Mn O3and La0.67Sr0.33Mn O3MOCVD thin films and bulk material[J].Phys Rev B,1996,53(21):14434-14444.
[14]Baaziz H,Tozri A,Dhahri E,et al.Size-induced Griffiths phase-like in ferromagnetic metallic La0.67Sr0.33Mn O3nanoparticles[J].J Magn Magn Mater,2016(403):181-187.
[15]Zhang N,Yang W,Ding W,et al.Grain size-dependent magnetism in fine particle perovskite La1-xSrxMn O3[J].Solid State Comm,1999,109(8):537-542.
[16]亓淑艳,郭丽琴,冯静,等.钙钛矿型复合氧化物La1-xSrxMn O3和(La0.7Sr0.3)1-yKyMn O3的结构及磁性研究[J].稀土,2008,29(1):23.
[17]Hwang H Y,Cheong S W,Radaelli P G,et al.Lattice effects on the magnetoresistance in doped La Mn O3[J].Phys Rev Lett,1995,75(5):914.
[18]唐永刚,严国清,毛强,等.一价Na元素对La Mn O3母体A位掺杂的磁电性质的影响[J].低温物理学报,2008,30(1):43.
[19]Maity S,Ray S K,Bhattacharya D.Phase,morphology and core-level electron spectroscopy of nano-sized La0.65Sr0.35Mn O3powders prepared by solution combustion synthesis[J].J Phys Chem Solids,2013,74(2):315-321.
[20]Wu Q H,Liu M L,Jaegermann W.X-ray photoelectron spectroscopy of La0.5Sr0.5Mn O3[J].Mater Lett,2005(59):1980-1983.
[21]焦正宽,曹光旱.磁电子学[M].杭州:浙江大学出版社,2005(1):272.
[22]Awana V P S,Tripathi R,Balamurugan S,et al.Magneto transport of high TCR(temperature coefficient of resistance)La2/3Ca1/3Mn O3:Ag polycrystalline composites[J].Solid State Commun,2006,140(9/10):410.
[23]Beyreuther E,Grafstrom S,Eng L M,et al.XPS investigation of Mn valence in lanthanum manganite thin films under variation of oxygen content[J].Phys Rev B,2006(73):155425.
[2]Beatriz R M,Irene L,Pilar J C,et al.Independent control of the magnetization in ferromagnetic La2/3Sr1/3Mn O3/Sr Ti O3/La Co O3heterostructures achieved by epitaxial lattice mismatch[J].Nano Letters,2016,16(3):1736.
[3]Barrionuevo D,Zhang L,Ortega N,et al.Enhanced tunneling electroresistance in Pt/PZT/LSMO ferroelectric tunnel junctions in presence of magnetic field[J].Integrated Ferroelectrics,2016,174(1):174.
[4]Huang W,Lin Y,Yin Y,et al.Interfacial ion intermixing effect on four-resistance states in La0.7Sr0.3Mn O3/Ba Ti O3/La0.7Sr0.3Mn O3multiferroic tunnel junctions[J].ACS Appl Mater Interfaces,2016,8(16):10422.
[5]Tan Y,Ju D Y.Electrical properties of Ag-La0.67Sr0.33Mn O3[J].Mater Sci Forum,2011,675/677:1101-1104.
[6]Moshyaga V,Belenchuk A,Huhn S,et al.Intrinsic antiferromagnetic coupling underlies colossal magnetoresistance effect:role of correlated polarons[J].Phys Rev B,2014,89:024420.
[7]凌一峰,刘翔,陈清明,等.固相法制备La2/3Sr1/3Mn O3:Agx多晶材料及其性能研究[J].热加工工艺,2013,42(16):25.
[8]殷学鹏,晏益志,陈清明,等.溶胶-凝胶法制备La0.67Sr0.33Mn O3:Agx多晶材料及其性能[J].热加工工艺,2014,43(20):84.
[9]刘翔,晏益志,陈清明,等.Ag掺杂对La2/3A1/3Mn O3(A=Ca、Sr、Ba)材料电学性能的影响[J].无机材料学报,2013,28(12):1307.
[10]张少春,刘翔,张辉,等.La2/3Ba1/3Mn O3:Agx多晶靶材制备及其性能[J].材料热处理学报,2013,34(6):1.
[11]Li J,Huang Q,Li Z W,et al.Microstructure modification and magnetoresistance enhancement by Ag doping in La2/3Sr1/3-Mn O3thin films prepared by dual-beam pulsed laser ablation[J].J Phys Condens Matter,2001,13:3419-3431.
[12]晏益志.Ag掺杂LSMO材料制备及LIV效应研究[D].昆明:昆明理工大学硕士学位论文,2014.
[13]Snyder G J,Hiskes R,Dicarolis S,et al.Intrinsic electrical transport and magnetic properties of La0.67Ca0.33Mn O3and La0.67Sr0.33Mn O3MOCVD thin films and bulk material[J].Phys Rev B,1996,53(21):14434-14444.
[14]Baaziz H,Tozri A,Dhahri E,et al.Size-induced Griffiths phase-like in ferromagnetic metallic La0.67Sr0.33Mn O3nanoparticles[J].J Magn Magn Mater,2016(403):181-187.
[15]Zhang N,Yang W,Ding W,et al.Grain size-dependent magnetism in fine particle perovskite La1-xSrxMn O3[J].Solid State Comm,1999,109(8):537-542.
[16]亓淑艳,郭丽琴,冯静,等.钙钛矿型复合氧化物La1-xSrxMn O3和(La0.7Sr0.3)1-yKyMn O3的结构及磁性研究[J].稀土,2008,29(1):23.
[17]Hwang H Y,Cheong S W,Radaelli P G,et al.Lattice effects on the magnetoresistance in doped La Mn O3[J].Phys Rev Lett,1995,75(5):914.
[18]唐永刚,严国清,毛强,等.一价Na元素对La Mn O3母体A位掺杂的磁电性质的影响[J].低温物理学报,2008,30(1):43.
[19]Maity S,Ray S K,Bhattacharya D.Phase,morphology and core-level electron spectroscopy of nano-sized La0.65Sr0.35Mn O3powders prepared by solution combustion synthesis[J].J Phys Chem Solids,2013,74(2):315-321.
[20]Wu Q H,Liu M L,Jaegermann W.X-ray photoelectron spectroscopy of La0.5Sr0.5Mn O3[J].Mater Lett,2005(59):1980-1983.
[21]焦正宽,曹光旱.磁电子学[M].杭州:浙江大学出版社,2005(1):272.
[22]Awana V P S,Tripathi R,Balamurugan S,et al.Magneto transport of high TCR(temperature coefficient of resistance)La2/3Ca1/3Mn O3:Ag polycrystalline composites[J].Solid State Commun,2006,140(9/10):410.
[23]Beyreuther E,Grafstrom S,Eng L M,et al.XPS investigation of Mn valence in lanthanum manganite thin films under variation of oxygen content[J].Phys Rev B,2006(73):155425.